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Subject: Re: AW: AW: Bug: Battery Charging with low voltage

Re: AW: AW: Bug: Battery Charging with low voltage

From: Linus Nielsen Feltzing <>
Date: Wed, 02 Feb 2005 20:45:51 +0100

Matthias Klumpp wrote:
> It's the same charger.
> I've taken the (only) one out of my car and I#m using it now at home,
> connected to a power supply (max. 5A).
> The conditions are the same. With ignition on in the car I have a input of
> 14V, that's the voltage I adjusted at the power supply at home.
> In both cases I get a output voltage (regulated by a LM317) of exactly
> 8.79V.

That's pretty low, if you ask me. 9V means a charging current of 140 mA,
so it will take up to 10 hours to charge the regular 1500mAh batteries.
A regulated supply should have at least 11V if you want the optimal
charging current of 350mA. This is even more important when you have
high capacity batteries (>1500mAh) with the Rockbox charging algorithm.
A too low charging current makes the charging take too long and the
algorithm will time out, and the batteries will never become full.

The Rockbox algorithm is designed for the original charger, or a
regulated 11-12V charger.

> Batteries are 6 month old and I bought them new.
> At least a ground problem inside the JB might not be the problem, because I
> tried with direct charging from the power supply with 12V and it was running
> perfectly over night.

It could still be a grounding problem, but let's put that aside for now.
I think the charging current problem is more important.

Received on 2005-02-02

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